With INSERT, UPDATE, DELETE and Merge SQL queries, you can modify Table data easily.
SQL: How to Use INSERT, UPDATE, DELETE and MERGE
insert /*+ append */ into kso.big_emp
insert /*+ append_values */ into dual (dummy)
How to use both append and append-values.
UPDATE SQL Query
set col1 = col1*1;
This query will do mass update. Instead, use INSERT with “APPEND”. Hint to improve performance.
DELETE SQL Query
delete from kso.skew2
This is also called mass delete. If the rows are more, it takes more CPU time. If we want to delete all the rows, always use TRUNCATE.
MERGE SQL Query
It is introduced with 9i. The basic functionality is when match, it will update. When not match it will insert.
MERGE INTO table_name
USING (subquery) ON (subquery.column = table.column)
WHEN MATCHED THEN UPDATE
WHEN NOT MATCHED THEN INSERT
Merge has its internal mechanism, it takes more CPU time. So always use insert with “APPEND” to delete bulk-rows. Here’s to read more on Merge SQL query.